It is known that images can be displayed by controllably frustrating TIR to switch selected pixels of a multi-pixel display between a reflective state in which light incident on those pixels undergoes TIR, and a non-reflective state in which TIR is frustrated at those pixels. It is also known that electrophoresis can be used to controllably frustrate TIR and controllably switch the state of pixels in such displays. Electrophoresis is a well-known phenomenon whereby an electrostatically-charged species moves through a medium due to the influence of an applied electric field. For example, an electromagnetic field can be controllably applied to move particles through an electrophoretic medium toward or away from an evanescent wave region to frustrate TIR at selected pixel portions of the region.
It is also known that repeated switching of a display which utilizes electrophoretically-mobile particles can result in a non-uniform distribution or clustering of the particles, gradually deteriorating the quality of images produced by the display over time. See for example Dalisa, A., “Electrophoretic Display Technology,” IEEE Transactions on Electron Devices, Vol. 24, 827-834, 1977; and Mürau et al, “The understanding and elimination of some suspension instabilities in an electrophoretic display,” J. Appl. Phys., Vol. 49, No. 9, September 1978, pp. 4820-4829. It has been shown that such undesirable clustering can be reduced by encapsulating groups of suspended particles in separate micro-fluidic regions. See for example Nakamura et al, “Development of Electrophoretic Display Using Microencapsulated Suspension,” Society for Information Display Symposium Proceedings, 1014-1017, 1998 and Drzaic et al, “A Printed and Rollable Bistable Electronic Display,” Society for Information Display Symposium Proceedings, 1131-1134, 1998.